Method of and apparatus for treating petroleum



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METHOD OF AND APPARATUS FOR TREATING PETROLEUM Sheets-Sheet 1 FiledApril 4, 1925 INVENTOR. BY M i. @la TTORNEY.

E 9 1927. Ju y J. w. LEWIS, JR

METHOD OF AND APPARATUS FOR TREATING PETROLEUM M4 i* l ATTORNEY.

July 19, 1927.

J. W. LEWIS, JR

METHOD OF AND APPARATUS FOR TREATING PETROLEUM Filed April 4, 1925 4Sheets-Sheet 4 mwN mvkb ok. -ll 1| l L... .N5 m Ill J .wh .IL NMATTORNEY.

Patented July 19, 1927.

iran sr-'ATES PATENT OFFICE.

.IosnPH vv. LEWIS, .'m., or PHILADELPHIA, PENNSYLVANIA, AssIeNon yro THEAr- LAN'rIo EEFINING comPANY, or PHILADELPHIA, PENNSYLVANIA, A coEPonA-'rien dr PENNSYLVANIA. i

METHOD F AND APPARATUS FOR TREAT'ING ZPETROLEUM.

Application led April 4, 1925. Serial No. 20,638.-

My invention relates to a method-of and apparatus for convertinghydrocarbons or mineral oils into lighter oils or oils of lower boilingpoints and more particularly my invention relates to a method of andapparatus for subjecting petroleum, petroleum. .dis-

tillate or petroleum residuum to conditions of temperature sure toeiiect and super-atmospheric presdestructive distillation, dissociationor cracking ot the oil for the production of light hydrocarbons such asnapthas, gasolines and burning or'kerosene oil.

This application is in part a continuation of my prior applicationSerialv No. 601,220, tiled November 16, 1922.

ln the well-known andl commonly used cracking processes one of theprincipal sources ot' trouble is in the deposition and accumulation ofcarbon and carbonaceous matter on the heating surfaces thereby cutting down the rate ofiheat transfer and, if permitted to continue, eventuallyrendering the apparatus inoperative.

ln accordance With my invention, the velocity of the oil over theheating surfaces 1s high thereby increasing the rate et heat transfer tothe oil and also largely preventing the deposition of any carbon orcarbonaceous matter which may be formed. My method is accordinglycharacterized by high rate of heat transfer into the oil and by highvelocity of the oil'over the heating surface, the oil and conversionproducts preferably remaining Wholl in the liquid phase. To effect thehigh y or largely rate of transfer of heat energy into the oil and toprevent local superheating, the oil is caused to flow in a helical orequivalent path Within a tube through Whose wall the heat is transferredinto the oil flowing in a stream of reduced cross section, in Contactwith the inner surface of qthe tube wall. the passage through thehelical or equivalent path serving also to sur and intel-mingle allportions of dthe oil and to bring them into substantially direct heattransfer relation with the inner surface of the tube -Wall and with thehelix surfaces.

'lhe helical path also serves by its smaller SSS ection to imparta highvelocity tothe Aheating surface and because of additional heat actuallyconducted into the oil and transferred to it by the helix itself.

' In accordance with my invention, the oil may be heated to .a highertemperature than is normally used and the time of the crackit@ ingreaction in the tubes may be thereby decreased. .When such hightemperatures are used, it 1s,l of course, necessary to employcorrespondmgly high pressures, particularly outhe lighter or lovierboiling oils *charged 55 or produced, to maintain the oil substantially1n the liquid phase. It is possible by means of my invention to obtainrelatively high conversions from high to louT boiling products in abriei cracking period with the 7@ deposition of very little carbon onthe l1eat ing surfaces and with low gas loss.

Further in accordance with my invention' there may be utilized areaction chamber in which the oil is retained While at crackingtemperature and in which the major portion or substantially all of thecracking takes l placev after the oil has been heated in the aforesaidhelical or equivalent path, in which the heat transfer is so increasedand the time se of heating, therefore, so decreased that the oil may beheated to a higher temperature than is otherwise possible Without anysubstantial cracking taking place in the tubes. The high velocity of theoil in the tubes at S5 the same time substantially prevents -thedeposition on the 'heating surfaces o the small amount of carbon whichis Jformed, thereby avoiding necessity of cleaning the tubes except atinfrequent intervals,. and so 9G lperniitting longer runs, and, at thesaine though it will be understood that oils lighter4 or heavier thangas oil or fuel oil may be treated in accordance with my invention forproducing oils of lower boiling points.

For an understanding` of some of the modes of practicing my method andfor an illustration of some of the forms my apparat-us may take,reference is to be had to the accompanying drawings, in which:

Fig. l is a vertical sectional View, some parts in elevation, ofapparatus embodying my invention.

Fig. 2 is a plan view of structure of the character illustrated in Fig.1.

Fig. 3 is a longitudinal sectional view, parts in elevation, showing anoil cracking tube and the helix member within the same.

Fig. 4 is a fragmentary View illustrating structure of the cooler orcondenser.

Fig. 5 is a flow sheet or chart.

Fig. 6 is a vertical sectional view, some parts in elevation, of amodified form of apparatus. A

Referring to Figs. l-el, F is a furnace or -combustion chamber in whichgas, oil or other fuel is burned, a blower B driven by motor M beingutilized, if suitable or desirable, for supplying air and inducingdraft. The hot gases pass from the furnace F through the ue a into themanifold tunnel or flue A, common to and extending in front of the endsof the several tubular cracking stills or units S, ten in number in theexample illustrated in Fig. 2.

Each still structurey comprises enclosing and surrounding brickwork band interior walls or partitions c, of brickwork or the like, forminglines or hot gas, passages d communicating with eachother at oppositeends of the structure and forming a continuous passage. Hot gases fromthe tunnel A are delivered into the lowermost flue passage d through theflue e, controllable by the "damper f. The gases'flow -to the right,Fig.

1, through the lowermost flue passage d, thence toward the left to themiddle flue passage (l, and thence toward the right through the upperHue passage d, and thence through Y the Hue passage g, controllable bythe damper h, to the manifold discharge iue C, controllable by thedamper z', to the chimney or stack D.

Extending through each of the flue passages d is a cracking tube T,there being preferably a single tube T for each flue passage d, thoughit will be understood that two or more tub'es T may be employed in eachflue passage. While the tubes T are shownl as disposed horizontally, itwill ybe understood that they may be disposed vertically or in anysuitable inclined position. Each of the tubes T terminates in the endchambers .7' and 7c, isolated by the endy walls b, b .from communication4with the flue passages d. Threaded on each end o f each tube T is acoupling flange m abutting against similar flanges n on the pipe membersor bends 0, bolts p serving to draw the flanges m and n snugly togetherto bearing thereon at the periphery of the threads or helical ribs, thecore r being provided at either or both ends, as at s, with a squaredend for reception of a Wrench or the like for rotating the helixstructure H when the apparatus is not in operation for loosening suchsmall deposits of coke, carbon or carbonaceous material as may adhere tothe inner wall of the tube T. By uncoupling the pipe sections 0 from atube T, the helix structure may be withdrawn from the .tubei T, cleanedand reintroduced, or a clean spare helix I-I may be immediatelyintroduced.

In a receivinv or pump house E is disposed a pump of any suitable type,to which the oil to be converted or treated is delivered through thepipe t,`raised in pressure, and delivered to the manifold u, with whichcommunicate the oil supply pipes fv, one for each still unit, a meter wand a valve being disposed in each of the pipes o.

Each pipe 'v delivers the oil, under pressure corresponding with thepressure utilized within the tubes T, to the heat exchange structure G,of any suitable character. In

the example illustrated, it comprises a tube for example, to 550 degreesF., and disy charged from the heat exchange apparatus through the valvea1 to the pipe b1, which connects with the inlet end of the tube systemat the left end of the lower tube T, Fig. 1. The oil, after traversingthe tubes T. is delivered from the tube'g/ through the valve c1 to themanually adjustable pressure-regulating or automatic pressure-reducingvalve V, Which delivers the oil to the pipe (l1 and thence to the coilor worm I of acooler or` condenser J through which cooling medium, aswater, is circulated, the saine entering, for example, at e1 anddischarging at f1.

The coil or worm I comprises lengths of tube or piping extending throughthe wall of the box or tank J and connected in series annealed drawnseamless steel tubing having with each other on the exterior thereof bythe return bends or couplings g1, Flg. 4, which are removable, so thatfroml the exterior of the cooler or condenser the interior of the tubesmay be accessible for cleaning therefrom carbonaceous or other deposits.

The several worms or pipe coils I of the dierent still units may bedisposed within one and the same box or tank J, as indicated lin Fig. 2.The discharge outlet of each,

worm or coil l'is connected through a pipe h1 and a. strainer l with areceiving drum or tank R, in which the-permanent or uncondensable gasand liquid oil separate from each other, the gas being drawn od throughthe the valve y and pipe k1 to the gas mani- 'old pipe K, which deliversinto any suitable gas storage tank. When `the cooler or condenser coilor worm I and drum R are. under super-atmospheric pressure, there may beemployed the pressure-reducing valve N, which delivers the gas to thepipe c'l at at* inospheric or slightly super-atmospheric pressure.Connecting with each pipe k1 may be provided a pipe m1, controlled by avalve nl, for Venting the pipe k1 to atmosphere.

i The oil is discharged from the receiver or drum R through a meter o1anda liquid-delivering trap or valve structure p1, which delivers theoil at lower pressure, if superatmospherie pressure exists upon the drumR, through the pipe g1, controlled by valve '111, to the manifold pipeL, which delivers to storage tank O, or any other suitable destination,'as for example, the tire stills Lhereinafter referred to in connectionwith Fig. 5. The meter o1 and trap p1 may be lay-passed through thevalve s1, a valve t1 iuteri-'ening between the trap p1 and the bynass..

' Extending across the several stills or pressure tube units is aplatform or walk Q, for convenience of the attendants.

'Running adjacent the Walk Q is a pipe U, communicating with a steamboiler for deliveringsteam for purposes of cleaning the pressure tubestructure. Connection is made to the pipe U for each tube unit through avalve u1 and a check valve 211 With the pipe b1, whereby steam may bepassed through the pipe 111 and through the tubes "l" for blowing themout or cleaning them either before or after removal of the helixstructures H, the check valve v1 preventing iiow of vapors or oil to thesteam pipe U when the pressure employed upon the tubes T during theiroperation is greater than that of the steam supplied to the pipe U.

The aforesaid cracking tubes T may be of any suitable material towithstand the pressures .and temperatures involved as herein described,and may be, for example. of

about .5 per cent carbon. y

way of example of apparatus which I Withfmy. invention, it may be statedthat the internal diameter of each tube T is two inches and its externaldiameter about 2.37 5 inches, each tube having a length of abouttwentyt'eet, of which about seventeen and a halt feet are disposedwithin the heating zone or flue d, Whose cross section may vary fromabout six inches to about fifteen inches square. The cylindrical core rof the helix struct-ure H is about one inch in diameter and thethickness of the thread about onequarter inch, whereby the cross sectionof the helical path for the oil is about onehal't inch deep andthree-quarters inch wide, the area of the cross section beingapproximately three-eighths of a square inch, or about one-eighth of thecross section of the tube. The pitch of the helix is about one inch,whereby for each linear foot ofthe tube T the oil niakesv twelve turnsaround the core 1'. Any suitable number of tubes T in series or tandemmay be utilized, '1nd the rate of delivery of the oil to be treated ispreferably such that the time required for the oil to traverse the tubeswill be of the order of tive to twenty-live minutes, and a period of tenminutes ais found suitable when using three of the above mentioned tubeshaving a length of about twenty feet with about seventeen and one-halffeet within the heating zone. lVith the aforesaid rate ot delivery ofoil to betreated into the cracking tubes, there is ell'ected, because othe helical path and its small cross section, velocity sufficient toprevent deposition of substantial quantitiesot carbon or carbonaceous material upon the heating surfaces. However, by utilizing more tubes inseries or tandem, thereby increasing the length of the helical path,thel velocity of flow correspondingly higher, when an equal quantity ofoil is pumped through in the saine total time of passage, therebyincreasing the rate ot' heat transfer. i

The pressure maintained upon the oil While traversinet the crackingtubes may range from about 200 to about 2000 pounds per square inch, andis effected largely or substantially entirely by the pump P.

The hot gases entering the left end of the lowermost flue passage d havea temperature of the order of 2000 degrees F. and at their discharge atthe entrance to the flue g have a temperature of the order of 1000degrees F. The oil entering the system of tubes T will have atemperature of the order of 550 degrecs, and at the discharge end of thetubes T will have a temperature of the order of 1000 degrees j, thetemperature of the oil dropping materially in the heat exchange'havesuccessfully employed in accordance i days duration the carbonproduced weighed out structure G in raising the incoming oil to theaforesaid temperature of about 550 degrees F. However, temperatures ofthe order of 7 50 degrees to 1050 degrees may be part of the path inopposite direction there- When operating under my method as abovedescribed, only very small quantities of carbon or carbonaceousmaterials are formed. In acontinuous run of about four as little as.05per cent of the Weight of the oil discharged from the drum R.

The treated oil obtained by the use of my invention may subsequently betreated in any suitable vor desirable way, such as by fractionaldistillatiomyielding distillates of r gasoline and naptha, lamp oil andgas oil,

leaving as bottoms fuel oil or heavylubri- -eating stock, as indicated,for example, in

Fig. 5. The various distillates may be chemically or physically treatedin any of the well known ways to yield standard products.

'The utilization of the helical path of the type above described isfurther of advantage in a system of the character indicated-in Fig. 6,wherein the oil is first 'heated for a relatively short period duringtraverse of the helical path at velocity higher than in the system ofFig. 1 and in liquid phase to raise itl to suitably high temperature,Withsubstantial cracking and then discharged into the reaction chamberZ, preferably heat-insulated, and of suitably large dimensions to retaina large bulk of liquid oil, where the majorportion or substantially allof the cracking is effected during the prolongedperiod during which theoil remains .in that chamber at suitable cracking temperature, the highpressure obtaining in the tubes, or suitably lower super-atmosphericpressure, being maintained in the reaction chamber. A

In this case, the rate of combustion in the furnace F may be suitablyhigher than in the system of Fig,` l to enhance rapidity of heating theoil in traversing the helical path and preferably also to 'cause ittoattain a relativelyV higher temperature vupon discharge from the tubesto the reaction chamber Z.

In theexample indicated in Fig'. 6, the oil to be treated is introduced,either cold or previously heated, under pressure by a suitable pump,corresponding With pump P of Fig. 1, at a2, into the tube system fromwhich it is discharged through the line b2 to the reaction chamber Z.

The'oil remains for a substantial period in the react-ion chamber Z, forexample, twenty minutes, and is discharged through the pressure-reducingvalve c2, together with some vapors, into the vaporizing chamber orfractionating tower d2, in which there may obtain substantiallyatmospheric pressure or preferably a super-atmospheric. pressure, forexample, forty pounds per square inch'. From the upper portion of thetower d2 there are drawn off through the line e2 certain vapors,comprising the lighter conversion products and some unconverted oil orcomprising lighter conversion products only, and delivered 'to thecooling worm f2 of the Water-cooled condenser g2. densate is thendelivered to the receiving drum R-wherein the gas is separated from thecondensate, the gas being drawn oli*l through l the line h2 and thecondensate .through the line 2, the condensate then being furtherrefined, as by distillation of the' general character indicated in Fig.5.

In the bottom of the vaporizing or fracf tionating tower d2 is collectedthe unvaporized portion of the material discharged fromthereactionchamber Z. This material is'of the character of tar or fueloil, which is dischz'izcrged through the worin jg of the tar cooler 2.

In a system of the character described in connection with Fig. 6, therate of transfer of heat into the charged oil in thetubes T is high, andthe period of heating relatively short, with no or at most only smallamount of cracking of the oil during traverse ofthe heating tubes.Furthermore, the velocity of the oil through the helical path issufficiently high to a'ord insuticient time for cracking and to ensurethat such small quantities of carbon or carbonaceous material as may beformed are not to substantial degree de- The conlli) posited upon theheating surfaces. l4`urtheiq The foregoing method as described in con-.f

nection with the use of the reaction chamber is preferred, thoughit'will be understood that other modes of use of reaction chamber may bepracticed. For example, a lower pressure may be used upon the tubestructure T and Within the reaction chamber, in

Which event vaporization may take place in that chamber., and the'vapors drawn olf ,therefrom for condensation, and there may 'be drawnoff from the reaction chamber tar point from higher boiling pointhydrocarbon oils, which comprisespassing the higher boiling point oil inliquid phase-in a helical path through a tubular passage in a streamWhose cross section ,is a small fraction of the cross 'section of saidtubular passage, and subjecting the oil While in said helical path tocracking temperature.

2. A tubular pressure cracking still structure comprising a tube, astationary helix member therein, said helix member having such pitch andhaving a core of such diameter that the cross section of the helicalpath is a small fraction of the cross section of said tube, means forforcing oil in liquid phase through said helical path, and heaterstructure surrounding said tube.

3. In the art of producing lower boiling point from higher boiling pointhydrocarbon oils the method which comprises rapidly passing the higherboiling point oil in liquid phase While under super-atmospheric pressureonce through a heating zone in a helical path through a tubular passagein a stream Whose cross section is a small fraction of the cross sectionof said tubular passage, subjecting the oil While in said helical pathto cracking temperature, thereafter delivering the hot oil into acracking zone, and effecting the major portionl of the cracking in saidcrack-l ing zone.

4. Still structure for cracking hydrocarbon oils comprising a tube, astationary helix member therein, said helix member having such pitch andhaving a core of such diameter that the cross section of the helicalpath is a small fraction of the cross section of said tube, means forforcing the oil in liquid phase under super-atmospheric pressure throughsaid helical path, heating structure surrounding said tube, and acracking chamber to which the heated oil is delivered from said helicalpath. l

JOSEPH W. LEWIS, JR.

